One-third of the arable land has been lost to erosion or sullied by pollution. Man-made chemicals and fertilizers used to improve crop yields persisted in soil for years, made it less fertile over time. Antibiotics in animal manure seeped out and caused degradation. Oil spills and environmental disasters have impacted large parcels of land. And all this is compounded by the sluggish pace at which new topsoil is formed—about 2.5 centimeters every 500 years. So, how can the essence of life on earth be preserved? Is it impossible or just too hard to complete?
Cleaning up soil is possible, but cumbersome. One method necessitates the dirt to be dug up, removed, and transferred to a treatment plant for decontamination. A better option would be to clean the soil where it lies. Ming Su, an associate professor of chemical engineering at Northeastern University, has developed a less costly and less labor-intensive way to decontaminate dirt. Ming describes his discovery—blasting soil with an infrared laser can quickly break down and eradicate a type of pervasive pollutant.
He had the idea to develop a new method for chemical decontamination and noticed the price of an industrial laser system had dropped significantly in recent years, making it feasible for large-scale use. He purchased a benchtop laser and tested it out on soil that had been sullied by the chemical DDE. A derivative of the notorious cancer-causing pesticide DDT, DDE was ideal for this study because it glows when exposed to ultraviolet light, making it easy to spot. He found that when he used the infrared laser to blast DDE-contaminated soil, and then scanned the soil with ultraviolet light, there was no glowing residue. The toxin disappeared. Su exclaimed, “The lasers could be installed on a plow structure so that a plow could dig into the ground and when a truck is moving, the laser can scan the whole area.”
Harminder Singh